8202632

hey all! 2009 CTTS. Over the last 2 days, I had to get my Cayenne jumpstarted on 2 separate occasions. Car starts up fine. Made 2 small trips, approx. 3 to 5 miles round trip. Next time i tried to start, just a click. Used jumper cables to jumpstart.

Attached is my Durametric report. I just replaced the battery 2 years ago (25,000 miles ago) with a Duralast Gold H9-DLG.

Been watching my volts via my Passport radar detector, and they start low and after driving for a few minutes, they are usually above 13.1. I've read tons of articles, and to be honest, I get confused with electricity, current, amps, etc, etc.

Got it charging on my CTEK all night, so maybe that will help.

I assume that if the volts are creeping up while driving, then the alternator should be fine? And that the battery may be bad. It has a 5 year warranty, so I may just go through the whole process of removing the thing and taking to my local autozone. Any thoughts or things i could look for to narrow down the focus? Thanks!

Ex968racer

Everything you provided leads me to believe it’s the battery. Start with the simple by getting the battery tested at autozone.

mcbit

Good start when cold and poor or no start when hot might well be the starter motor. Changed mine a year ago at around 120,000 kms.

deilenberger

Given the number of error codes shown in the Durametric readout - it appears low voltage conditions have occurred. That typically sounds like battery. You mention reading the voltage with your radar detector when it's running. 13.1V is low for a charging voltage even at idle. I'd hope to see 13.4-13.7V at idle and higher off idle. Thing is - we don't know how accurate the voltmeter on a radar detector is (since that's not it's primary function) and how good a connection the power feed to it has.

I'd suggest buying a simple VOM. Even the Harbor Freight $4 ones (free with the purchase of..) are better than nothing. Then measure the voltage under the hood as the jump start terminals.

One other suggestion - fix this before you have to jump start it again. Jump starting was fine when cars were primitive with no solid state electronics. Just connecting the clips to the jump start terminals is capable of creating a slight arc - which can cause a high-voltage transient to go through the cars electrical system. Most stuff now is protected against that with an input voltage limiting diode - but probably not all. The high voltage pulse can damage the electronics in the car - and that gets very expensive very fast.

So best thing is - avoid jumpstarting it. Hooking a charger up (with it turned off when you hook it up) is pretty safe - better to do that and let it restore the battery so you can at least get it started and to a shop to have it replaced.

v10rick

Comparing the Cayenne instrument cluster voltmeter with a Fluke industrial DVM, both matched exactly. Off idle the reading was 14V.

Your voltage regulator/alternator could be shot or there is a load which is pulling down the output of the alternator.

One way to determine if the load is excessive...with the engine off and doors closed measure the current drain at the battery.

Depending on the options you should measure a fraction of 1A.

If higher, isolate the offending circuit by pulling fuses until the current drops suddenly.

You may want to start with the amp fuse.

This is not a task for parts changers. There are numerous modules connected to the battery which are always hot.

Consult a qualified automotive electrician to help isolate this.

deilenberger

The 957 CTTS doesn't have a dash voltmeter unfortunately. The put a boost gauge in it's place.

Travis

It’s likely the battery. Having gone through this recently, I had a bad alternator at 185+K miles.

Doing a simple load test by turning on all the electrical gizmos with engine off and voltmeter hooked up. Battery voltage held steady. 12.7-8 volts. (3 year old battery)

The Cayenne also will barf out a warning if the alternator is not charging. Big red warning on your cluster plus the voltmeter will be at something less than 12v. That was NOT a fun repair.

Since your battery is only 2 years old, take advantage of the warranty.

8202632

ok, so before going out of town for a few days, I decided to remove the battery to take to autozone for testing. As recommended by the other members here, I also did a voltmeter test and the passport radar is accurate to within .1v!!

I heard the water sloshing around and it gave me an idea to check the water level in the battery. I unscrewed each of the 6 caps and added distilled water and it took about 20oz total to fill to the recommended level in each chamber.

So i did this and put the battery back and attached it to my CTEK for the duration of my vacation. Got back and obviously it was reading 14.1V. Disconnected it and drove it today and it has been running at about 13.7 volts with the lights on, 4 zone ac on, wipers on, and ipod running.

I know this may only be a bandaid to an already ailing battery, but wanted to let everyone know that it seems like voltage is up and more stable based on my prior issues. I will continue to monitor now that I'll be using the pepper as I normally do. Keeping my fingers crossed.

I read somewhere that these batteries are "dry shipped", so it may make sense if you purchase a new one to make sure the retailer has filled it correctly from the get go. Also keeping in mind that the battery may already be toast if the levels were not good for a while. Will keep yall posted.

deilenberger

Thanks for posting an update. Yeah - a partly filled battery only has part of it's capacity.. hopefully yours wasn't damaged physically by being partly filled. It doesn't sound as if your charging system is overcharging - so it's not a case of boiling off the electrolyte..

Although - just a FWIW - on a BMW I owned - we were going away for a few months on a cross-country trip - so I plugged my Accumate charger into the wall and connected it to the battery on the car. Came back and found the battery dead. It was under warranty - so I got a replacement, but when I took the old one out, it was super light compared to the replacement. The charger had failed - and failed in full-charge mode, boiling off the electrolyte. You may want to use a VOM to keep an eye on the charging rate when you leave it connected to your CTEK.

Accumate declined to warranty my charger... or fix it. Or even offer me a discount on a new one.

8202632

Today with normal use of about 4 trips and on/off cycles the battery voltage under load was anywhere b/w 13.5v to 14.1!

8202632

been keeping a keen eye on this. Voltage under load has been 13.6 to 14.3 consistently now. Unbelievable how adding water has helped save this battery!!!

Marv

Acid is not acid without water (hydrogen), that's why.

You boiled off the water in the battery over time and that is why they tell you only to add distilled water to a battery, not more acid.

Good work!